Air-curing copolymer latices

Abstract

Air-curing copolymer latices are described. The preferred copolymer latices are prepared by emulsion copolymerization, in the presence of a free radical polymerization catalyst such as inorganic or organic peroxide polymerization catalysts, with a blend (in % by weight based on the total weight of all monomers used) of (a) about 1% to about 20% of dicyclopentadienyl acrylate or dicyclopentadienyl methacrylate, (b) about 99% to about 20% of an alkyl acrylate or methacrylate, including mixtures of such monomers, and preferably a lower alkyl acrylate or methacrylate in which the alkyl groups contain from 1 to 4 carbon atoms, (c) 0% to about 5% of acrylic acid or methacrylic acid, and (d) 0% to about 85% of other monoethylenically unsaturated copolymerizable monomers. As examples of other copolymerizable monomers which may be used as component (d) may be mentioned: higher alkyl acrylates and methacrylates in which the alkyl groups contain from 5 to about 18 carbon atoms, acrylamide, methacrylamide, acrylonitrile or methacrylonitrile; also vinyl esters (e.g. vinyl acetate, vinyl propionate of vinyl chloride), styrene and alkyl vinyl ethers. The novel air-curing latices of the present invention are particularly suitable for use in paints and other coating applications since the films obtained therefrom continue to cure on standing in air, as evidenced by a marked increase in their resistance to solvents, such as methyl ethyl ketone. The cure can be accelerated to a significant degree by heating the films and/or by incorporating a few percent of a drying agent in the latex.